The rational design of microemulsions for chemically enhanced oil recovery: peaks to thermo

J.G.E.M. Fraaije
University of Leiden, NL

Keywords: oil & gas recovery, microemulsion

Summary:

There can be no doubt that the development of surfactants and polymers for microemulsion formation in crude/brine mixtures would be a great asset in our portfolio for enhanced oil recovery. While we await results of various pilot implementations, it is also important to realize what we have learnt so far, and to project to the future. In short, the quest is for computer-assisted rational design strategies, that would enable a shorter development cycle for a given crude, and, even more ambitious, would enable the deployment of novel surfactants. We believe that from a scientific point of view, there are two key elements for success: (a) a proper chemical analysis of crude oils, brines and additives - since without such analysis a molecular design approach is not possible, (b) a thorough theoretical understanding of emulsion stability in reservoir conditions - according to the 'Method of Moments' that we developed in collaboration with Shell. We also understand that new protocols will demand new ways of working in the industry, in that we will have to realize that the limitation to a SARA analysis, or simple statistical regressions, are not sufficient for an optimal design strategy. In an ideal world, a thorough spectrometric and or chromatographic analysis, supplanted by advanced molecular modeling techniques, would have to be part of a deployment of any emulsion recovery program. This what we refer to as 'from peaks to thermo to property'. Such integrated methods do not exist yet. But given that we are amidst a revolution in instrumental analysis, and equally revolutionary rapidly increasing availability of cheap computational power, we will need to develop such methods fast: Big Data abounds. In the talk I will review the molecular thermodynamics behind the 'Method of Moments', including comparison with older approaches such as Winsor 'R' ratio and the Salager QSAR. I will also include examples of the modeled interface of realistic living heavy oils emulsions, containing naphthenic acids, asphaltenes and waxy paraffin. I will conclude by offering speculations how we believe the new tools should be implemented in the industry.